The present invention comprises a new and distinct hybrid Spiraea cultivar hereinafter referred to by the cultivar name ‘NCSX2’. This new Spiraea was developed through a breeding program at Mills River, N.C. ‘NCSX2’ was selected from a population of seedlings grown from a controlled cross of Spiraea ‘Zelda’ (U.S. Plant Pat. No. 21,976 P2, diploid) as the seed parent and Spiraea japonica H2007-101-003 (unpatented, tetraploid) as the pollen parent. The first asexual propagation of ‘NCSX2’ was carried out in July 2012 by rooting stem cuttings at a research nursery in Mills River, N.C. and has been asexually reproduced repeatedly by vegetative cuttings over a 5-year period. ‘NCSX2’ roots readily from softwood cuttings treated with a basal dip of 4,000 to 5,000 ppm indole butyric acid (potassium salt) in water. ‘NCSX2’ has been found to retain its distinctive characteristics through successive asexual propagations.